Narrated Abu Huraira Radi Allaho Anho : Allah's Apostle Sallallaho alaihey wasallam said,
The signs of a hypocrite are three:
Whenever he speaks, he tells a lie; and
whenever he promises, he breaks his promise; and
whenever he is entrusted, he betrays (proves to be dishonest)
Sahih Bukhari, Volume 8, Book 73, Number 117